Mitel Announces Closing of Initial Public Offering

April 27, 2010

Mitel Networks Corporation (Nasdaq:MITL), a leading provider of IP-based communications solutions, today announced that it has closed its initial public offering of 10,526,316 common shares at a price to the public of US$14.00 per common share for gross proceeds of USD$147,368,424. Mitel's common shares began trading on the NASDAQ Global Market under the symbol "MITL" on April 22, 2010.

The offering was made through an underwriting syndicate led by BofA Merrill Lynch, J.P. Morgan, and UBS Investment Bank, who acted as joint book-running managers. Piper Jaffray, Genuity Capital Markets, and JMP Securities acted as co-managers for the offering.

"This is an exciting milestone for Mitel," commented Don Smith, CEO, Mitel Networks. "It is a testament to the commitment of our employees, our strong customer and partner relationships, and our position as a leader in the IP-based business communications market. We look forward to continued growth with our focus on unified communications solutions that deliver tangible business benefits to our customers globally."

Certain shareholders of Mitel have granted to the underwriters an over-allotment option, exercisable for a period of 30 days from April 21, 2010. Under the option, the underwriters may purchase from the selling shareholders up to 1,578,947 common shares at a price of US$14.00 per common share. Mitel will receive no proceeds from any exercise of the over-allotment option by the underwriters.

This press release shall not constitute an offer to sell or a solicitation of an offer to buy, nor shall there be any sale of these securities in any state, province or jurisdiction in which such offer, solicitation, or sale would be unlawful prior to registration or qualification under the securities laws of any such state, province or jurisdiction.

Some of the statements in this press release are forward-looking statements that reflect Mitel's current views with respect to future events and financial performance. Statements that include the words "may," "will," "should," "could," "estimate," "continue," "expect," "intend," "plan," "predict," "potential," "believe," "project," "anticipate" and similar statements of a forward-looking nature or the negatives of those statements, identify forward-looking statements. In particular, this press release may contain forward looking statements pertaining to, among other matters: general global economic conditions; our business strategy; our plans and objectives for future operations; our industry; our future economic performance, profitability and financial condition; the costs of operating as a public company; and our research and development expenditures. Forward-looking statements are subject to a variety of known and unknown risks, uncertainties and other factors that could cause actual events or results to differ from those expressed or implied by the forward-looking statements, including, without limitation, the risk factors described under the heading "Risk Factors" in our prospectus, dated as of April 21, 2010, which has been filed with the U.S. Securities and Exchange Commission and Canadian securities authorities. These statements reflect our current views with respect to future events and are based on assumptions and subject to risks and uncertainties. We operate in a very competitive and rapidly changing environment. New risks emerge from time to time. In making these statements, we have made assumptions regarding, among other things: no unforeseen changes occurring in the competitive landscape that would affect our industry; a stable or recovering economic environment; no significant event occurring outside the ordinary course of our business; and stable foreign exchange and interest rates. While we believe our plans, intentions, expectations, assumptions and strategies reflected in these forward-looking statements are reasonable, we cannot assure you that these plans, intentions, expectations, assumptions and strategies will be achieved. Our actual results, performance or achievements could differ materially from those contemplated, expressed or implied by such forward-looking statements as a result of various risks and uncertainties, including the risks factors described under the heading "Risk Factors" in our prospectus, dated April 21, 2010, which has been filed with the U.S. Securities and Exchange Commission and Canadian securities authorities. Except as required by law, we are under no obligation to update any forward-looking statement, whether as a result of new information, future events or otherwise.

About Mitel

A global market leader in business communications powering more than two billion business connections, helps businesses and service providers connect, collaborate and provide innovative services to their customers. Our innovation and communications experts serve more than 70 million business users in more than 100 countries. For more information, go to www.mitel.com and follow us on Twitter @Mitel.